Impact wrench checkers



y 1966 E. T. ABLE ETAL IMPACT WRENCH CHECKERS 2 SheetsShe-et 1 Filed July 9, 1964 INVENTORS. EDWARD 7. ABLE WILLARD KRlE GER ATTORNEY July 19, 1966 T. ABLE ETAL IMPACT WRENCH CHECKERS 2 Sheets-Sheet 2 Filed July 9, 1964 ATTORNEY United States Patent Colo.

Filed July 9, 1964, Ser. No. 381,327 Claims. (Cl. 73-1) This invention generally relates to a device for checking the output of torque measuring wrenches and more particularly for checking the output of power driven impact wrenches. Impact wrenches are power-driven wrenches designed for tightening threaded connections, such as screws, bolts, nuts, etc. by imparting rotation thereto through a rapid series of impacts until a predetermined load has been placed upon the work piece. It is necessary to accurately and uniformly preset such wrenches to the desired maximum delivery torque and, since the impacts of the wrenches are only momentary, it is difiicult to determine their maximum output.

The principal object of this invention is to provide an impact wrench checker to which a power driven impact wrench may be applied and which will accurately indicate the maximum torque output of the wrench.

Another object of the invention is to provide such an impact wrench tester which will indicate upon a dial the output torque of the wrench being tested and which will retain the maximum indication until reset.

'A further object of the invention is to provide an impact wrench checker that will be adaptable to various sizes of wrenches and to wrenches of either clockwise or counter-clockwise rotation.

Other objects and advantages reside in the detail construction of the invention, which is designed for simplicity, economy, and efliciency. These will become more apparent from the following description.

In the following detailed description of the invention, reference is made to the accompanying drawing which forms a part hereof. Like numerals refer to like parts in all views of the drawing and throughout the description.

In the drawing:

FIG. 1 is a side elevational view of the improved wrench checker;

FIG. 2 is an enlarged front elevational view of the checker of FIG. 1;

FIG. 3 is a vertical, longitudinal section therethrough taken on the line 3--3, FIG. 2;

FIG. 4 is a fragmentary, detail, longitudinal, section through the forward extremity of a tension bar employed in the checker to be later described; and,

FIG. 5 is a fragmentary detail section taken on the line 55, FIG. 3.

The impact wrench checker of this invention employes an anchor housing adapted to be mounted upon any sturdy work table support through the medium of suitable mounting bolts inserted through mounting openings 11 in base flanges projecting oppositely outward from the housing 10.

The housing 10 is formed with a circular gauge cavity 12 in its upper portion with an anchor cavity 13 there- =below. An anchor bearing cup 14 is inset in the anchor cavity 13. The bearing cup is provdied with a forward peripheral flange 62 which is bolted to the housing 10 through suitable cap screws 15. A tubular anchor sleeve 16 is formed on and extends concentrically rearward from the anchor bearing cup 14 and is welded, as indicated at 18, to the forward extremity of an elongated anchor tube 17 which extends rearwardly from the housing 10. An annular thrust bearing assembly 19 is positioned in the bearing cup 14. An enclosing mechanism 3,261,198 Patented July 19, 1966 cover 55 is secured to the back of the housing 10 by suitable cap screws 56.

A tension bar 20 extends throughout the combined length of the anchor tube 17 and the anchor sleeve 16. The'ztension 'bar is hollow throughout the major portion of its length. The hollow terminates adjacent the forward extremity in a solid portion 57 as shown in FIG. 4. The tension bar 20 is mounted in suitable roller bearings 21 in the anchor sleeve 16 and extends forwardly within, but out of contact with, the thrust bearing assembly 19. The rear extremity of the tension bar 20 has an enlargment 22 which is rigidly locked in a counter-sink in the rear extremity of the anchor tube 17 by suitable locking screws 23. An enlarged head 24 is formed on the rear terminus of the tension bar 20 which bears against the rear extremity of the anchor tube 17 to prevent forward movement of the rear extremity of the tension bar. Thus, it can be seen that the rear extremity of the tension bar is fixedly locked and anchored against movement in any direction with reference to the housing 10. The forward extremity, however, can move longitudinally in the bearings 21 when tension is applied to the tension bar 20.

The tension is applied through the medium of an externally threaded tension bar adapter 25 which is rigidly bolted to the forward extremity of the tension bar through the medium of an axial bolt 26. The tension bar adapter 25 is formed with tenons 27 which fit into receiving mortises in the forward extremity of the tension bar to prevent relative rotative movement therebetween. An internally threaded nut 28 is threaded upon the externally threaded tension 'bar adapter 25. The nut 28 is provided, at its rearward extremity, with a flange 29 which bears against and extends within the thrust bearing 19, so that rotation of the nut will apply tension to the tension bar 20.

The nut 28 extends forwardly of the head of the bolt 26 and this forwardly extending portion contains a splined cavity 30 for receiving a .splined drive socket element 31 having a concentric square passage 32 for receiving the square output shaft of an impact wrench. The drive socket elements 31 are interchangeable for dilferent sizes of output shafts on impact wrenches and are rigidly locked in position in the nut 28 by means of a suitableclamp screw 33.

It can be seen from the above that if the output shaft of an impact wrench is inserted in the passage 32 of the drive socket element 31, and operated, it will rotate the nut 28 at each impact of the wrench causing it to climb the threads on the tension bar adapter 25 to apply, through the medium of the bolt 26, tension upon the tension bar 20 to stretch the latter forwardly.

A measurement of the forward movement of the forward extremity of the tension bar is used in this invention to provide an indication of the maximum torque developed by the impact wrench. This is accomplished by forming a circumferential groove 34 in the tension bar adjacent the forward extremity thereof. The groove 34 is provided with an inclined, forward wall 35 against which the lower extremity of a vertical sensing rod 36 is constantly urged through the medium of a compression spring 37. The spring 37 is compressed between a suitable gear frame 38, mounted on the back of the housing 10, and a spring washer 39 mounted on the sensing rod 36.

The lower extremity of the sensing rod 36 has a reduced diameter portion 40 which extends through a roller bearing 41 into contact with the inclined wall 35 of the groove 34. The upper extremity of the sensing rod is drilled to receive a toothed rack rod 42 which extends upwardly into the gear frame 38 through a suitable antifriction bearing 43. Rack teeth 44 are milled into one side of the rack rod 42 and mesh with pinion teeth formed in a rack pinion shaft 45 mounted in suitable bearings 46 in the gear frame 38 so that vertical movements of the sensing rod 36 will be translated into rotary movements of the rack pinion shaft 45.

These vertical movements of the sensing rod are multiplied through the medium of a spur gear 47 mounted on the rack pinion shaft 45 and meshing with a pinion 48 formed on a pointer shaft 49 mounted in suitable bearings 50 in the gear frame 38 and extending forwardly into the gauge cavity 12. An index pointer hand 51 is mounted on the forward extremity of the pointer shaft 49 to indicate positions upon an annular scale 52 on a transparent dial face 53 which is circumferentially adjustable in the open face of the gauge cavity 12 by means of a suitable, removable mounting ring 54.

It can be seen that if an impact wrench is applied to the drive socket element 31 and operated, the nut 28 will be rotated in a clockwise direction to react against the thrust bearing assembly 19 to cause the internal threads thereon to act against the external threads on the tension bar adapter 25 to impart a stretch on the tension bar 20. This stretch will move the inclined side Wall 35 of the groove 34 forwardly allowing the reduced portion 40 of the sensing rod 36 to descend. This downward movement is transmitted from the rack rod 42 and through the gear train to the pointer 51 causing it to rotate counterclockwise to give an indication on the index dial 52 of the maximum impact which has been applied by the wrench.

The friction between the threads on the nut 28 and the threads on the tension bar adapter 25 together with the friction at the thrust bearing assembly 19 prevents the return of the nut 28 between impacts of the Wrench so that the index pointer hand 51 remains stationary at the maximum indication on the scale until reset. The resetting is accomplished by reversing the wrench to unscrew the nut 28 to release the tension in the tension bar 20.

The checker can be adapted to various sizes'of wrenches by interchanging the splined drive socket elements 31. The checker can also be adapted to test left hand wrenches by replacing the nut 28 and the tension bar adapter 25 with a left hand threaded nut and a left hand threaded adapter. Thus, the checker can be efficiently adapted to 7 check the output of all types of impact Wrenches.

The transparent dial face 53 can be released and I- tated by removing the mounting ring 54 so that the scale 52 can be rotated to accurately place the index markings in proper relation to the index pointer hand 51 before use. This can be accomplished by applying a load to the drive socket element 31 with a torque wrench of known accuracy and then rotating and setting the dial face with the reading on the dial face corresponding to the reading on the torque wrench. It can also be accomplished by a pre-setting kit including a deformation meter 60 provided with an actuating plunger 61. The meter 60 is mounted on the extremity of a pre-setting rod 59 which can be threaded into a threaded socket 58 in the solid portion 57 of the tension bar 20 so as to project from the rear extremity of the latter as shown in broken line in FIGS. 3 and 4. For presetting purposes, the plunger 61 is placed against the head 24 and the meter 60 is set on the pre-setting rod 59 so that the meter indicates 0 when all loose play has been removed between the wrench and the tension bar 20. The dial face 53 is then set in accord With the meter indications. The pre-setting kit forms no part of the present invention.

A tension spring 63 is tensioned between an eccentrically positioned dowel pin 64, in the spur gear 47, and an attachment screw 65 in the gear frame 38. This spring constantly maintains the teeth 66 of the rack pinion shaft 45 in contact with the teeth 44 on the rack rod 42 so that there is no lost motion between the sensing rod 36 and the gear train when the sensing rod starts to descend. The spring 63 also resists wavering vibration of the pointer hand under the vibration of the impact Wrench.

' While a specific form of the improvement has been described and illustrated herein, it is to be understood that the same may be varied, within the scope of the appended claims, without departing from the spirit of the invention.

Having thus described the invention, what is claimed and desired secured by Letters Patent is:

1. A wrench checker comprising: a housing; an anchor tube fixedly mounted at its forward extremity in said housing and extending rearwardly therefrom; a tension bar extending longitudinally within said anchor tube; locking means affixing the rear extremity of said tension bar. to said anchor tube; an annular thrust bearing in said housing surrounding the forward portion of said tension bar; a rotatable internally threaded nut on the forward extremity of said tension bar and bearing against said thrust bearing; wrench engaging means on said nut for imparting rotation to said nut to cause it to react against said thrust bearing to stretch said tension bar longitudinally; and gauge means actuatable in consequence of the stretch imparted to said tension bar to indicate the amount of torque being applied to said nut V by said wrench.

2. A wrench checker as described in claim 1 in which the wrench engaging means comprises a drive socket element removably mounted in said nut and provided with a non-round socket in axial alignment with said tension bar to receivethe drive element of a socket wrench and a releasable locking means for locking said drive socket element against rotation in said nut.

3. A wrench checker as described in claim 1 having a tension bar adapter removably mounted on the forward extremity of said tension bar and extending into said nut, said adapter having external threads engaging the internal threads of said nut to impart tension to said tension bar in consequence of rotation of said nut.

4. A wrench checker as described in claim 3 having a bolt extending through said adapter and into said tension bar for holding the former onto the latter and means on said adapter engaging said tension bar for preventing relative rotation therebetween.

5. A wrench checker as described in claim 1 in which the gauge means comprises: a groove formed in said tension bar at right angles to the axis thereof; a forwardly inclined wall in said groove; a sensing rod slidably mounted in said housing; spring means urging one extremity of said sensing rod against said forwardly inclined wall; and indicating means connected with the other extremity of said sensing rod to indicate the amount of movement of said sensing rod occasioned by longitudinal movement of said tension bar.

References Cited by the Examiner UNITED STATES PATENTS RICHARD C. QUEISSER, Primary Examiner. 

1. A WRENCH CHECKER COMPRISING: A HOUSING AN ANCHOR TUBE FIXEDLY MOUNTED AT ITS FORWARDLY EXTREMITY IN SAID HOUSING AND EXTENDING REARWARDLY THEREFROM; A TENSION BAR EXTENDING LONGITUDINALLY WITHIN SAID ANCHOR TUBE LOCKING MEANS AFFIXING THE REAR EXTREMITY OF SAID TENSION BAR TO SAID ANCHOR TUBE; AN ANNULAR THRUST BEARING IN SAID HOUSING SURROUNDING THE FORWARD PORTION OF SAID TENSION BAR; A ROTATABLE INTERNALLY THREADED NUT ON THE FORWARD EXTREMITY OF SAID TENSION BAR AND BEARING AGAINST SAID THRUST BEARING; WRENCH ENGAGING MEANS ON SAID NUT FOR IMPARTING ROTATION TO SAID NUT TO CAUSE IT TO REACT AGAINST SAID THRUST BEARING TO STRETCH SAID TENSION BAR LONGITUDINALLY; AND GAUGE MEANS ACTUABLE IN CONSEQUENCE OF THE STRETCH IMPARTED TO SAID TENSION BAR TO INDICATE THE AMOUNT OF TORQUE BEING APPLIED TO SAID NUT BY SAID WRENCH. 